I have isolated as recombinant DNA clones, regions of the Drosophila genome that contain tandem copies of the 70K protein heat-shock genes. These genome DNA fragments will be used to map the boundaries of stable and primary transcripts of the 70K protein genes. The sequence homology distal to the 5' terminus of different transcriptional units will be examined. Studies on chromatin structure will be carried out in parallel to attempt to correlate transcriptional activity and aspects of chromatin structure. The 70K protein genes are approximately ten-fold repeated and encode a family of closely related proteins. The relationships of the different proteins with the different gene copies will be studied in detail. I have isolated cDNA clones carrying sequences from other heat-shock genes as well. Genome DNA fragments will be isolated for these genes and mapping of the transcriptional units carried out. Nucleotide sequence relationships adjacent to all heat-shock gene transcriptional units will then be investigated. In situ hybridization experiments will attempt to assign each type of gene to a cytological locus.